Hydraulic shock absorber structure



Nov. 16, 1943. G. M. MAGRUM 2,334,340

HYDRAULIC SHOCK ABSORBER STRUCTURE Filed May 26. 1941 zmraz-fizzr 6212ms: M /%aewv.

Patented Nov. 16, 1 943 4,3

v 2,334,340 v a YpnA LIc snocKnBsoRBEn STRUCTURE GervaseM'. Magrum,Bufialo, N. Y.,.assignor, by

mesne assignments,,to Houdaille-Hershey Corporation, Detroit,.Mich.,acorporation of Mich "Applicatim M e r erialN0. 395,148 1; r Claim l )H,a a

. This invention relates to hydraulic shock absorbers and particularlyto improved, means: for controlling the flow of the displaced hydraulicfluid. The invention is particularly useful in hydraulic shock absorbersof the rotary type or so called fI-lo'udaille typein whichvalve as,-sembly mounted withinthe piston structure controls the flow between thehydraulic working chambers-as for example the type of shock ab so'rberdisclosed in Peo et 'al. Patent 2,004,902, June 11, 1935, orfPeo PatentNo. 2,079,869, May 11, 1937. y

In thistype of'shOCk absorber referred-to, a valve seating member isseated in the hollow hub of the piston structure and is bored to receivea cylindrical valve for controlling an oriflce in the seat member, thevalve beingprovided with a stem structure extending through a along thevalve andreturn' it' to the working chambers. i

eflicient arrangement for accomplishing the ObJGCtS Of my invention isdisclosed on the drawing in which 7 r V v Figure '1 is a verticaldiametral sectional :view

on planI-I ofFigureZy r l a it Figure 2 is a sectionfon plane IIII ofFigure 1; and

Figure 3 is a section on plane III-III of Fig ur L. m Briefly describingthe shock'absorber, it comprises a cup-shaped'housing lil receiving nearits outer end a bearing wall I l'from which abutbore in the pistonstructure shaft, by which stem structure rotary movement may be impartedto the valve for adjustment thereby of the orifice. With thisarrangement, the hydraulic fluid displaced under heavy pressure willtend to leak out between the valve and the seat member" and intotheshaft bore, particularly after thevalve becomes more or less worn. Insome shock ab: sorbers the shaft bore has been connected 'th u aventpassageway with the shock 'absorbe'r "reservoir, as for example inPet) et a1. 2,004,902, the leakage fluid thus finding'its way from theshaft bore into the reservoir. How'- ever, with this arrangement, whenthe leakage becomes more pronounced,- particularly when H and coverl9'having opposed recessesforming Patent 5 the hydraulic fluid becomesheated and of de- ,5

creased viscosity, the leakage flow may become greater than thereplenishing flow into the working chambers from the reservoir and're'sulting air pockets in the working chamberswould materiallyinterfere with eflicient shock absorber action. v U

In some shock absorbers it is more desirable to omit the passageway fromthe shaft bore to the reservoir andvto keepbthe shaft bore closed, asshown in Peo Patent 2,079,869. However, with such arrangement, theleakage into the shaft bore will pile up and exert back pressureagainstthe valve seat displace it from leakage and cause noisy operation. a I,The important object of myinvention is to provide simple means forpreventing unbalanced its seat which would result in pressure againstthe valve seat member which member tending ,to loosen it or ment walls12 extend to the base of the housng, pins I3 holding the wall andabutment against rotational displacement inthe housing; The bearing walljournals the pistonshaftfl extending from the cylindrical piston hub 15between the abutments l2; the hub having vanes 16 which,v with theabutmentsjdeflne hydraulic Working chambers I1, ll" and I8, I8, 1 Aclosure member or cover "l9 screws into the outer end of the housing l0to. axially hold the wall 'H and abntments I2 in place, the walla'reservoir "20 for hydraulic fluid whichis fed to the working chambersthrough check valve controlled passageways 2!, in a manner well known inthe art. When the shock absorber is employed on a vehicle, the housingis usually Secured to the vehicle body and the outer end ofthepistonshaft is connected bysuitable levers with the vehicle axle so thatupon relative move,- ment between axle and body the piston structurewill be oscillatedwithin the housing to displace fluid in the workingchambers.

=The piston shaft has the bore 22 therethrough and at its inner end thepiston'hub has a 1argerbore or chamber 23 into which extends the boss onthe housing base for ;pro-

viding a bearing for'the pistonstructure. In

the piston hub is the intermediate bore 25 in which is located the valveseating member 26 which is held against the shoulder 21 as by peeningagainst its inner end of the annular v tongue of metal 280i thepistonhub.

the loosened seat membenwould would. tend to loosen such membenjand withsuch means operable to intercept the leakage fluid .The seat member '26has the axial borefl I forming a seat for the cylindrical valve 30. vTheseat member has the circumferential channel 3| which registers with thepassageways 32, 32' in the piston hub, these passageways communieatingwith the high pressure hydraulic work ing chambers ll, ll respectivelyof the shock absorber. The chamber 23 in the pistoahub ektending Vcommunicates through passageways 33, 33 with the low pressure workingchambers I8 and [8' respectively.

'The seating member 26 has the circumferentially. extending orifice slot34 therethrough. The

valve 30 has the passageway or bore 35 extending thereinto from theinner end thereof and the valve has the; circumferentiallyfextending;port 36, for connecting the valve passageway 35 with the orifice slot.The valve is rotatably adjustable in shaft bore there can be noaccumulation of fluid or build up of pressure in the shaft bore againstthe valve seat member.

During down stroke of the shock absorber when the fluid is displacedfrom the working chambers l8, l8 to the chambers ll, ll, th fluidpressure is directed against the inner end of the valve seat the seatmember for overlapping by its port 31:; v of the orifice slot 34 for thedesired degree of orifice slot exposure and shock absorber resistance tothe displaced hydraulic-fluid: flowidnring: operation of the shockabsorber. 4

The valve 30 is connectedbya stem 31 with a head 38 rotatable in theouter end of the shaft bore 22 for setting of the valve for adjustmentof; its port relative to the orifice slot 34. On the drawings this stem31 is shown in the 'formof a helica-l thermostat secured at its innerendoto the outer end of the valve and at its outer endto he he d o aevalyewi lbeautoma c l y set.- by temperature forg nt ol Q h fQifiC 3A-To hold the valve against-axial;displacementin the. valve seat, a rod, 31' is pro d d hi hh s ball and socket connection at itsvenclszwithlthe.valizeand. he dresnectivelyr 3 In the shock absorber shown, thehighgpres: ure flow during rebound; movement; or the vehicle springswith which the shock absorber is, as; sociated would be; from the workinchambers in |;1 through the passageways-3. 2 and 5 and through theorifice 34,int,o the valve boreand;the chamber '23, andfromtherethronghthe passage-x 'ways:- 33, 33.! .to the workin chambersvI13, UH.

. sure against the seat member. andatheipres'sure might'become"suflicient to bend the securing means. 28 for" the seat member so thatthe; seat memberwouldf become loosened. and: more leakage intotheshaftbore would result; The. important: object oft-my. invention istuprevent the leakage from reaching the 'shafta bore, and I aocomplishthis by providingtheinterceptin channel- 4fl in--and aroundthe valve-3'0at apointinwardly-of-lthe outer 'end of the seatin -member 26; and-" aconnection between this-"intercepting channel and the outer endefthevalveborebya port orpassageway 4 l r with this arrangement any leakageflow'outwardly between theva-lve and the seat'm'emberwill be interceptedby the channel and prevented from reaching the shaftbore we; will be;conducted by the passage} is tothe valve bore 7 from, where it-"Wouldflowinto; the chamber 23; and to the shockabsorber-lowpres sureWorking'chambers I8 and i8"? the suction effectin these workingchambers; duringrebound operation of the shock absorber-assisting inwithdrawing the leakage fluid from the intercepting channelfor returntothe Working circuit; The leakage being thus prevented fromyreachin-gthe member in a direction to; hold it limits seat. During= the boundoperation 'of the 1 shock. absorber, the orifice will be at normalopening and will "offer less resistance to flow than during the reboundstroke, and there will be little tendency for fluid to leak past thevalve toward the shaft boreflxany fluidflow between the valve and seatmember-being intercepted by the channel 40 and drawn-backinto theworking circuit by the suction effect in theworking chambers l1 and llbefore-it canrreachthe shaft bore. The intercepting arrangement thusprevents flow into the shaftboreduring both bound and rebound operationof the shockabsorberr ventedgto'the reservoir, as injPeo et al.. Patent2,004,902,, leakagepast'the Valve will be unable toybuild uprany,pressure against the valvefs'eat. However, the leakage, after aperiodlof useofthe shock absorber may become' /so'g'reat, that thisdrainage from the working circuit'may be at'a greaterrate. than therate,of replenishment of j v the-workingcircuit through the replenishing passages between-"the reservoir and the working at;

cuit and the operation of the shock absorber'" would be seriouslyimpaired. All this. can be readily avoided, by providing" anintercepting channeland path forreturn of the leakage fluid directlyback into the working circuit. Thus',

whetherthe shaftbore iscl'osed', or is'v'ented to the reservoir, myimproved arrangementtwillpree 4 vent, accumulation of leakage in theshaft bore but; will intercept leakag e and return "itdrrectly into.the, hydraulic working 'circuit and thereby prevent any unbalancedpressure] conch tionagainst the valve seating member tending to displaceor fl'oojsen it full; eff ciency ofth'e shock absorberbeing thusmaintained;

II haveshown a practical and efficient-embodismentofi my invention but Ido:, not desire to be Iirnjitejdl to exact construction; arrangementchambers of a, hydraulic. shock absorberiof the I type'described inwhichv a 'vaned piston operating in the chambers and drive shaftextending there from haveabore therethrough, comprising a valve seatmember seated intsaid bore intermediate the ends thereof and having anorifice: for metering the flow. of hydraulic fiuid. displaced in thework ing chambers during;operatic-n of the shock} absorbet, acylindrical; valveextending throughsaid seat'. member andihaving' aport, said valve being adjustablerotatablyin vsaidseat member forcooperationof its port with said orifice 'to determine the ,efl?ectivesizejjofisaid orifice, saidvalve} having 1 a; passageway therein; forconnecting said port Withlithe inner endfof saidbore, saidvalve-outiwardly of its port and'inwardly' of the outerend 0i said seatmember having acircumferentially r iney ha nel the ein or interceptingany between the valve and seat member toward 011m? i o fi f 1 99 1 C t Pn In; shock'absorbers where the shaft' here; is a be made. Without de ig om i h f QP tending' tc flow'from thework-ing chambers 2. V'alvingassembly for controlling the dis-- placed fluid flow in the hydraulicworking chambers of a hydraulic shock absorber in which a vaned pistonstructure operates and has a bore therethrough, comprising a seatingmember seated in said bore to form a wall between the inner and outerends thereof, a hollow valve plug extending through said seat member,said seat member and said valve plug having passageways cooperable todefine a metering orifice for the hydraulic fluid flow caused by saidpiston structure, said valve plug outwardly of said metering orificeandinwardly of the outer end of said seat member having a circumferentiallyextending channel connected with the interior of said valveplug forintercepting and returning directly into the hydraulic working chambersany fluid which may tend to leak therefrom between said valve plug andseat and to thereby prevent such fluid from reaching the outer end ofsaid bore.

, 3. Valving assembly for controlling the displaced fluid flow in thehydraulic working chambers of a hydraulic shock absorber of the typedescribed in which a vaned piston structure operating in the chambershas a bore extending therethrough, comprising a valve seat member seatedin said bore and having an orifice for metering the flow of displacedhydraulic fiuid during operation of the shock absorber, a valveadjustable in said seat member and having a port cooperable with saidorifice to determine the efiective metering size thereof, said valvehaving a passageway connecting its port with the inner end of said bore,and means between said valve and seat member for intercepting the flowof leakage fluid from the working chambers toward the outer end of saidbore and returning the fluid directly to the working chambers to therebyprevent unnecessary loss of fluid from the working chambers duringoperation of the shock absorber.

I GERVASE M. MAG-RUM.

